Lonely Planet is the leader in travel books. This isn't just my opinion, I've met many other travelers who won't go anywhere without the appropriate LP book. Africa on a Shoestring is a great guide, with information on places to stay and what to see, for travelers who don't want to spend a fortune and aren't afraid to get out and actually experience the local culture.
That being said, I'm really disappointed in parts of this book. As the market leader, LP should be able to keep its books properly updated. Yet many country sections start with: "We were unable to do on-the-ground research in (country_name), so some information in this chapter may not be reliable". While this is understandable in someplace like Liberia or Cote d'Ivoire where the national security situation is volatile, it's inexcusable for countries like Nigeria. Yes, there are some problem areas in Nigeria, and Lagos can indeed be chaotic. But Nigeria is not Lagos. And Nigeria is not the Niger Delta. I certainly hope that they manage to update some of these chapters for the next edition.
In the interest of full disclosure, here are the countries LP didn't bother to update for this edition: Guinea-Bissau, Nigeria Sierra Leone, Liberia, Cote d'Ivoire, Congo-Brazzaville, CAR, Congo-Kinshasa, Burundi, Somalia, Angola. Libya is listed as potentially being partially unreliable.
If you're traveling to Africa, my advice is to get this book _and_ the Rough Guide to whatever region of Africa you're going to. If you're going somplace that LP's book doesn't cover, look for a specific book that covers it. My last bit of advice for Africa travelers is to roll with the punches. There aren't nearly as many folks going to Africa as there are to Europe, so the information on Africa isn't as cutting-edge new. That hotel you read about and planned on staying in tonight? It burned down six months ago. But there are always other options, so just relax and take it easy.